A humanoid bipedal robot having two legs extended from a hip of a lower part of a trunk, two arms extended from shoulders on right and left sides of the trunk, and a head containing an imaging system for vision of the robot mounted on an upper part of the trunk is disclosed, for example, in Japanese Patent Laid-Open Publication No. SHO-62-97005 and Japanese Patent Laid-Open Publication No. SHO-63-150176.
The applicant of the present invention presents a technique of stabilizing control in attitude of a bipedal robot based on an inverted pendulum dynamic model in Japanese Patent Laid-Open Publication No. HEI-5-337849 (U.S. Pat. No. 5,459,659) as an attitude stabilizing control system for a bipedal robot.
This robot attitude stabilizing control based on the inverted pendulum dynamic model is purported to torque-control ankles of the robot on the basis of behavioral characteristics in swings of the robot in its upper position. A robot stabilized in attitude in such a manner is more easily stabilized in attitude when the center of gravity of the entire robot is positioned higher than when the center of gravity is positioned lower.
There is a power supply system in which power for operating legs, arms and other components of a bipedal robot is supplied to the robot via a cable from outside. This supply system, however, limits the movable range of the robot by the existence of the cable, and it is troublesome to handle the cable. For these reasons, it is preferred to mount a storage battery as a power source for operating a robot.
However, in mounting a storage battery to a robot, there are several problems to be solved with respect to a large weight of the storage battery, an appearance of the robot made larger to some extent by the battery, the relationship between the storage battery and a rotation axis with which an upper part of a trunk of the robot to which the storage battery is mounted is made rotatable relative to a lower part of the trunk, and securing sufficient capacity of the storage battery.